The present invention relates to video encoding technology; and particularly to apparatuses and methods for video processing and recording.
Video compression is an important part of video storage and transmission. Digital video contains spatial and temporal redundancies, which may be encoded without significant sacrifice. Spatial redundancy is based on the similarity in color values shared by adjacent pixels. Video encoding employs intra-frame spatial encoding on redundant color values using DCT (Discrete Cosine Transform) and quantization. Temporal redundancy refers to identical temporal motion between video frames, providing smooth, realistic motion in video. Video encoding relies on prediction, more precisely, motion-compensated prediction, of temporal encoding between frames. Video encoding utilizes, to create temporal encoding, I-Frames, B-frames and P-frames. An I-frame is an intra-coded frame, a single image heading a sequence, with no reference to previous or subsequent frames. It encodes only within the frame with no reference to previous or subsequent frames. P-frames are forward-predictive frames, encoded with reference to a previous I- or P-frame, with pointers to information in a previous frame. B-frames are encoded with reference to a previous reference frame, a subsequent reference frame, or both. Motion vectors employed may be forward, backward, or both. Video encoding quantizes the coefficients produced by applying a DCT to 8×8 blocks of pixels in an image and through motion compensation. Quantization is basically division of the DCT coefficient by a quantization scale related to quality level, with higher indices for greater encoding but lower quality, and lower indices for the reverse.
Video recorders (e.g. MPEG recorders), however, in the beginning, reduced resolution of original video data to encode due to its process capability, resulting in poor output quality.
Home recording apparatuses, such as VCD or DVD recorders, are unable to record video data in high resolution due to storage capacity. The resolution of the recorded data is much lower than the resolution of large-size displayer For example, the resolution of DVD recoding data is in 720×480. But the resolution of displayer is up to 1920×1440. FIG. 1 is a diagram of the architecture of a conventional video data processing system. Video apparatus 10 acquires and processes video data, and outputs the processed data to a displayer 20. After receiving original video data 30, video encoding device 100 encodes the original video data 30 in a predetermined resolution and stores it in storage device 200, such as VCD, DVD-RW or hard drive. To generate high quality video data, video decoding device 300 reads video data from the storage device and decodes it contingent upon the required resolution of a displayer 20, for example, the decoded data may be scaled up by a scaling device 400 or 401 in the displayer 20 to bring the decoded data to the required resolution. In conventional video data, serious distortion occurs during scaling up because the original video data 30 is encoded in the lower predetermined resolution by the video encoding device 100.
FIG. 2 is a diagram of conventional MPEG-2 single layer video encoding. The original video data 30 is input to the video encoding device 100 and frames therein are encoded according to frame type. I-frame directly undergoes DCT. Conversely, P- or B-frame first undergoes ME (Motion Estimation) to generate MV (Motion Vector), and MC (Motion Compensation), differential measurement between the original video data 30 and re-constructed video data 31 is calculated, and spatial data converted into frequency data by DCT. The converted frequency data is quantized by a relevant quantization matrix corresponding to the frame type to reduce complexity. The quantized two-dimensional data is converted to one-dimensional data and undergoes VLC to generate encoded data. Note that the original video data 30 and re-constructed video data 31 are generated in a predetermined resolution. When resolution of displayer 20 exceeds the predetermined resolution, serious distortion occurs.